Understanding the structure and properties of geological formations is important for a wide variety of applications in well and reservoir management, monitoring, and remediation. Fluid sensing devices can detect certain properties of fluids to aid in attaining this understanding. However, available fluid sensing devices typically couple to a wireline tool or to a drill string or drill string tool such as a logging-while-drilling (LWD) tool and, as such, are isolated from annular regions between a casing string and formation. Therefore, available fluid sensing devices cannot detect many conditions that would be of interest to an operator during or after cementation processes when operators place cement in the annular regions. Some available fluid sensing devices may also be incapable of detecting the presence of low amounts of oil-based muds or other undesirable fluids in the annular region.